In electric vehicles and hybrid vehicles, a battery is used for traction power generation. Other motor vehicles require an on-board battery for operation. It is often necessary to transmit electric power from an external power source to the vehicle. Wired solutions (so-called plug-in solutions) are already known, in which an electric plug-in contact and an associated feed line are used for connecting an external stationary power source to the vehicle in order to charge its battery. Further more convenient solutions are known, where electric power is transmitted from a stationary coil (called transmission charging coil from now on) to a vehicle-side coil by an alternating magnetic field, wherein the vehicle-side coil serves as receiving charging coil.
When taking a general look at the stray field losses in this wireless transmission system there arises the desire to design the transfer of power with a maximum degree of efficiency in order to reduce the stray field to an absolute minimum.